Recording decelerometer



G. DE CHANGY RECORDING DECELEROMETER Sept. 8, 1959 2 Sheets-Sheet 1 Filed Sept. 24, 1956 Sept. 8, 1959 G. DE CHANGY RECORDING DECELEROMETER 2 Sheetsf-S heet 2 Filed Sept. 24, 1956 United States Patent RECORDING DECELEROMETER Gilbert de Changy, Clarmart, France Application September 24, 1956, Serial No. 611,451

Claims priority, application France September 23, 1955 3 Claims. (Cl. 346-7) This invention relates to the apparatus of the type designed to record on a sheet of paper the different decelerations to which a vehicle carrying the recording apparatus is subjected, and wherein the aforesaid decelerations are recorded in the form of separate lines having a common origin but lengths varying as a function of the deceleration value.

Now it is the essential object of this invention to provide an apparatus of this type, also called decelerograph, in which the paper sheet or tape is replaced by a disc adapted to pivot about an axis, the different lines indicating the decelerations to which the apparatus is subjected having a substantially radial orientation.

Figure lis a plan view from above of the apparatus.

Figure 2 is a similar View showing the apparatus without its cover.

Figure 3 is a cross-sectional view of the same apparatus,

-the section being taken upon the line III-III ofFig. l.

' The inertia block 21 is mounted on one end of anarm 22 pivoted at its other end about a pivot 23. 'A' strip 24 extends substantially at right angles from this arm 22 and carries at its free end a pen or stylus 45. A ratchet wheel 25 is fixed rigid with the lower portion of a revolvable shaft 26. A resilient spring 27 prevents the ratchet wheel from rotating in a clockwise direction and the rotation of this ratchet wheel in a counter-clockwise direction is controlled by a pawl 28 pivotally mounted at 29 on the aforesaid arm 22 and normally urged by a light return spring 30 into engagement with the teeth of the ratchet wheel 25.

A compression spring 31 hearing with one end against a fixed abutment 32 and guided by a rod 33 passing through an aperture formed for this purpose in the arm 22 constantly urges this arm 22, and therefore the inertia block 21 carried thereby, against a stop 43. A cam-forming member 44 is adapted to be engaged by the operative end of the pawl 28 to prevent it from driving the ratchet wheel 25 by more than one tooth at a time, whereby a step-by-step drive is applied to this ratchet wheel. Besides, an adjustable stop 35 is adapted to be engaged by a projection 34 formed on the pawl 28 to lock the latter against motion upon completion of each driving pulse.

The stylus 45 extends upwards and is adapted, due to the inherent resiliency of the strip 24, to exert a light elastic pressure on the inner or lower face of a disc 39. The disc may advantageously consist of a waxed sheet of paper protected by adequate means and rotatably rigid with the ratchet wheel 25 and shaft 26; to this end, the disc 39 is clamped between a shoulder or collar portion 41 rigid with the shaft 26 and a pane of glass 40, the clamping action being provided by a nut 42 screwed on the registering threaded end portion of shaft 26.

The compression spring 31 is so adjusted that the angular movement of the inertia block 21 about its axis 23 ice as well as that of the stylus 24 for the maximum deceleration value contemplated are below a predetermined maximum corresponding for example to the penultimate concentric scale or reference line printed on the disc 39.

This maximum amplitude cannot be overstepped, except in case of shock or like abnormal occurrence in which case the inertia block 21 will engage a stop 36 carried by a guiding rod 37 slidably mounted in a supporting bracket 46 and constantly urged to its outward position by a coil spring 38.

Thus, in case of sudden, excessive shock, the revelant linetraced on the disc 39 by the stylus 45 will overstep the aforesaid penultimate scale line and reach the last or outermost scale line, and the impact will be revealed immediately.

The recording disc 39 carries preferably concentric circular scale lines corresponding to the different amplitudes of the angular displacements of the stylus as a function of the decelerations to which the apparatus is subjected.

The complete mechanism may be mounted on a base 47 protected by a cover 48 adapted to be secured by means of four bolts 49; this cover has an upper face 50 which, when the cover is closed, is level with the shoulder or collar 41 and comprises a central aperture just sufficient to allow this shoulder or collar 41 therethrough. The cover 48 further carries another, outer cover, hingedly mounted on a pin 51 and constituting a bezel or like circular frame 52 carrying a glass plate 53. The disc 39 and the lines traced thereon by the stylus 45 are visible through the glass plates 40 and 53. To replace the recorded disc 39 with a fresh one it is sufficient. to lift the outer or circular frame 52 about its hinge pin 51 and to release the central nut 42 to free the glass plate '40; it is not necessary to remove the cover 48 proper. The complete mechanism of the decelerograph is concealed and protectedby the cover 48 and the only apertures formed in this cover are the aforesaid central aperture surrounding the collar 41 and a curvilinear slot 54 concentric to the pivot pin 23 for the passage of the stylus 45.

An arrow 55 directed at right angles to the arm 22 carrying the inertia block 21 when the mechanism is in its inoperative condition may advantageously be provided at the top of the apparatus to indicate that the latter must be so placed on the vehicle to be tested that the arrow indicates the direction of motion of the vehicle.

The apparatus described hereinabove and shown in the attached drawings may be utilized for testing both horizontal and vertical decelerations, as well as shocks in different directions; the position of the apparatus employed is subordinate to the desired results.

To avoid the too frequent substitution of fresh discs for recorded ones these may be replaced by a recording tape paid off between two rollers or spools, the winding roller or spool being driven stepwise; nevertheless, the mechanism described and shown hereinabove may also be used with a recording tape mechanism.

What I claim is:

1. In a recording decelerometer for measuring and recording deceleration of a vehicle, in combination, a pivotally mounted arm, an inertia mass mounted on said arm for effecting pivotal movement of the arm away from a rest position in response to deceleration forces of said vehicle when the decelerometer is disposed in the vehicle in a given position relative to the forward movement of the vehicle to allow the mass to sense and respond to said forces, a limit stop against which said arm bears when in said rest position, a damping spring disposed bearing on said first arm for compression thereby when the arm leaves the rest position, a rotatable shaft, a record disc carried by said shaft for rotation thereof, a stylus constantly in writing engagement with said record disc, means operatively connecting the stylus to said arm for angular displacement thereof in the same direction and extent of angular displacement of said arm, drive means perated by said arm to rotate said shaft a given angular extent for each displacement of said arm away from said rest position in response to deceleration forces above a given value thereby to position the record disc in separate angular positions for recording each deceleration of the vehicle seperately thereon.

2. In a recording decelerometer for measuring and recording deceleration of a vehicle, in combination, a pivotally mounted first arm, an inertia mass mounted on said arm for effecting pivotal movement of the arm away from a rest position in response to deceleration forces ofsaid vehicle when the decelerometer is disposed in the vehicle in a given position relative to the forward movement of the vehicle to allow the mass to sense and respond to said forces, a limit stop against which said arm bears when in said rest position, a damping spring disposed bearing on said first arm for compression thereby when the arm leaves the rest position, a rotatable shaft, a record disc carried by said shaft for rotation thereof, a stylus constantly in writing engagement with said record disc, means comprising a second arm fixed substantially nortrial to the first arm operatively connecting the stylus to said first arm for angular displacement thereof in the same direction and extent of angular displacement of said first arm, drive means operated by said first arm to rotate said shaft a given angular extent for each displacement of said first arm away from said rest position in response to deceleration forces above a given value thereby to position the record disc in separate angular positions for recording each deceleration of the vehicle separately thereon.

3. In a recording decelerometer for measuring and recording deceleration of a vehicle, in combination, a pivotally mounted arm, an inertia mass mounted on said arm for effecting pivotal movement of the arm away from a rest position in response to deceleration forces of said vehicle when the decelerometer is disposed in the vehicle in a given position relative to the forward movement of the vehicle to allow the mass to sense and respond to said forces, a limit stop against which said arm bears when in said rest position, a damping spring disposed hearing on said arm for compression thereby when the arm leaves the rest position, a rotatable shaft, a record disc carried by said shaft for rotation thereof, a stylus constantly in writing engagement with said record disc, means operatively connecting the stylus to said arm for angular displacement thereof in the same direction and extent of angular displacement of said arm, drive means operated by said arm to rotate said shaft a given angular extent for each displacement of said arm away from said rest position in response to deceleration forces above a given value thereby to position the record disc in separate angular positions for recording each deceleration of the vehicle separately thereon, said drive means comprising, a ratchet wheel fixed on said shaft and having peripheral teeth, a pawl pivotally connected to said arm engageable with the wheel teeth successively for effecting rotation of said wheel the extent of one tooth every time the arm moves away from the rest position and records a deceleration.

References Cited in the file of this patent UNITED STATES PATENTS 164,031 Philips June 1, 1875 671,952 Daellenbach Apr. 16, 1901 868,055 Wolfe Oct. 15, 1907 877,198 Jerauld .c Jan. 21, 1908 1,010,725 Coleman Dec. 5, 1911 1,104,250 Dake et a1 July 21, 1914 1,139,247 Wilson May 11, 1915 1,992,134 Toewe Y I Feb. 19, 1935 FOREIGN PATENTS 557,920 Great Britain a- Dec. 10, 1943 576,596 Great Britain Apr. 11, 1946 600,306 Germany July 19, 1934 

